1. Field of the Invention
The present invention generally relates to heat dissipation devices, and more particularly to a heat dissipation device having a heat pipe for cooling an electronic component, such as an integrated circuit package.
2. Description of Related Art
Electronic components, such as central processing units (CPUs) comprise numerous circuits operating at high speed and generating substantial heat. Under most circumstances, it is necessary to cool the CPUs in order to maintain safe operating conditions and assure that the CPUs function properly and reliably. In the past, various approaches have been used to cool electronic components. Typically, a finned metal heat sink is attached to an outer surface of the CPU to remove the heat therefrom. The heat absorbed by the heat sink is then dissipated to ambient air. The related finned metal heat sink is made of highly heat-conductive metal, such as copper or aluminum, and generally comprises a solid metal base for contacting with the CPU to absorb the heat therefrom and a plurality of fins formed on the base for dissipating the heat. However, as the operating speed of electronic components has increased markedly in recent years, heat sinks which transfer the heat only by metal conduction are insufficient for this purpose and as a result the heat from the bottom of the metal heat sink cannot be transferred to the whole heat dissipation device quickly enough.
Heat pipes, which operate by phase change of working liquid sealed in a hollow pipe have been widely used due to their excellent heat transfer properties. Accordingly, heat dissipation devices equipped with heat pipes are widely used. U.S. Pat. No. 6,163,073 shows an integrated heat sink with heat pipes. The heat sink has a cast base plate and vertically extending fins, the fins being cast integrally with the base plate. The base plate has elongated grooves that extend along a bottom of the base plate. Elongated heat pipes are disposed in the elongated grooves for contacting with heat sink and the CPU. The related art indicates that this structure reduces thermal gradients in the heat sink. However, the area of the base in contact with the CPU is greater than the area of the heat pipe in contact with the CPU. The heat of the base of the heat sink still cannot be transferred to the whole heat sink quickly enough.
Another technique for dissipating heat includes a base including an envelope filled with working liquid (i.e. vapor chamber). This kind of heat dissipation device includes a heat sink in contact with the base. The working fluid circulates between a liquid phase and a gaseous phase in the vapor chamber in such a manner that heat is taken up at a point that is in contact with the CPU, and the heat is released at a point in contact with a heat sink. This structure has better heat dissipation, but it is complex and expensive.
Accordingly, what is needed is a heat dissipation device with heat pipes which has an enhanced heat dissipation performance and inexpensive.